Our program is concerned with the role of the renin-angiotensin-aldosterone system in homeostasis, in hypertension, and in congestive heart failure. Presently, our major thrust is an attempt to define the pathogenesis of experimental renal hypertension. In this endeavor, we are concentrating on evaluation of the role of the renin-angiotensin system by the use of continuous chronic angiotensin II blockade. For these studies we are using three animal models--in the dog, rabbit, and rat. Also, it is planned to study separate kidney function the development and maintenance of chronic two-kidney hypertension in the dog and the rabbit. In addition, we will be evaluating the role of the renin-angiotensin-aldosterone system in the pathogenesis of spontaneous hypertension in the rat. Studies are continuing on the mechanisms which regulate renin release in the dog and special emphasis will be given to the role of the macula densa as an intrarenal receptor.